Contrast-enhanced ultrasound sonography combined with strain elastography to evaluate mandibular lymph nodes in clinically healthy dogs and those with head and neck tumors

Use of New Ultrasonography Methods for Detecting Neoplasms in Dogs and Cats: A Review

The aim of this literature review was to present the novel imaging modalities elastography and contrast-enhanced ultrasonography. We provided an overview of the concepts and applications of each technique for the investigation of neoplastic and metastatic tumors in dogs and cats. Studies on elastography are based on the elasticity and deformation of the evaluated tissue. The information obtained from the different types of elastography can aid in the detection and differentiation of malignant and benign structures. Descriptions of elastography studies in several organs and tissue in veterinary medicine reported that, in general, malignant tumors tend to be more rigid and, therefore, less deformable than benign lesions or in comparison to the healthy parenchyma. Contrast-enhanced ultrasonography is based on the intravenous injection of contrast media constituted by microbubbles. This imaging modality can be performed in nonsedated animals and provides information on the tissue perfusion, allowing the investigation of macro- and micro-circulation. Studies on different organs and tissues were performed in dogs and cats and revealed a tendency of malignant tumors to present faster transit of the contrast media (time to wash-in, peak and wash-out). These advanced techniques can be associated with other imaging modalities, aiding important information to the well-established exams of B-mode and Doppler ultrasonography. They can be used as screening tests, potentially representing an alternative to the invasive sampling methods required for cytological and histopathological analysis.

Shear wave velocity measurements obtained in different regions are repeatable for presumed normal canine lymph nodes: A pilot study

Shear wave elastography (SWE) has been applied as a noninvasive method for predicting regional lymph node (LN) metastases in human and veterinary patients. However, published studies describing standardized protocols and repeatability of this technique are currently lacking. The objective of this prospective, pilot, observer agreement study was to determine whether different shear wave velocity (SWV) measurements obtained in different regions of presumed normal canine LNs would be repeatable. Two imagers consecutively performed shear wave elastography of submandibular, superficial inguinal, and popliteal LNs in 10, clinically healthy adult dogs. Ten elastograms of each LN were acquired by each imager. In each adequate elastogram, three regions of interest (ROIs) were placed in the softest and stiffest region of the LN. Additionally, one ROI was drawn covering the entire LN. In each ROI, mean, median, and maximum SWVs were calculated. Mean values for the mean, median, and maximum SWVs varied from 2.33 to 3.10 m/s, 2.32 to 3.10 m/s, and 2.61 to 4.09 m/s, respectively. Intra- and interobserver agreements were acceptable. Superficial inguinal LNs demonstrated the highest intra- and interobserver agreement, followed by the popliteal and the submandibular LNs, respectively. Using the different measurements (mean, median, or maximum SWVs) had no significant effect on the intra- and interobserver variability, neither did the region (softest, stiffest, or entire LN). Findings indicated that all evaluated measurements and regions could be used to obtain reliable elastography data of presumed normal canine LNs. Clinical trials in dogs with cancer are necessary to compare SWVs of metastatic LNs with the reported SWVs and evaluate whether various measurements and regions can also be used in metastatic LNs.